By Karuna Eberl
Updated on Aug. 29, 2024
If your check engine light is on, you may save time and money by identifying the problem yourself with a car diagnostic scanner.
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We were halfway across the country when our van’s check engine light came on. We took it to a dealer, who charged us thousands of dollars for parts that didn’t fix the problem.
That’s when we bought our first car diagnostic scanner. Within an hour we figured out the actual problem, which ended up being a $150 part that took less than an hour to replace.
We’ve since heard similar complaints from many other people. A lot of it has to do with the evermore complex electrical and emission systems and sensors in today’s vehicles. But if you have a little wrenching knowledge, you don’t necessarily have to be at the mercy of the repair shop.
Here’s what a car diagnostic scanner can do for you, and those annoying warning lights on your dashboard.
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A car diagnostic scanner — aka an on-board diagnostics scanner or an OBD2 code reader — is a device that communicates with your vehicle’s computer system to retrieve information about its performance and potential problems.
“Since 1996, every car, light truck, SUV, minivan and hybrid sold in North America has been required to have an on-board diagnostic [OBD2] system,” says Keith Andreasen, an Automotive Service Excellence (ASE) certified master technician and tool product manager at Innova Electronics.
“It monitors a vehicle’s systems that trigger the check engine light and alert drivers about issues related to emissions, fuel economy and drivability.”
It helps DIYers and professional automotive technicians figure out what’s wrong with a vehicle.
Some scanners just read codes, while others are more complex, monitoring real-time data. All OBD devices plug into a standardized port, usually under the steering wheel.
All OBD devices read diagnostic trouble codes (DTCs) generated by the vehicle’s onboard computer. “The scanner can display these codes in a human-readable format, helping users identify the problem area,” says Andreasen.
Other functions of car diagnostic scanners can include:
While the capabilities of OBD2 devices vary depending on their price and manufacturer, in general they cannot:
It’s a valuable tool for anyone who likes to work on their car, because it lets you problem-solve repairs without paying an auto mechanic to do it.
“A consumer with little automotive repair experience can use a diagnostic scanner to check a vehicle for road trip readiness, see if their car is ready to pass an emissions test, or better understand why the check engine light is on,” says Andreasen.
If you think a car diagnostic scanner might be good for you, here’s a good entry level one and a more sophisticated model.
If you’re not ready to buy one yet but your check engine light is on, most auto parts stores carry basic code readers and will read your code for free on the spot.
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